Cataracts from our colony of the Emory mouse, an animal model for human senile cataract, will be further characterized by the determination of such biochemical parameters as SH, S-S, tryptophan and tyrosine in chromatographic fractions of the soluble lens proteins. In more opaque lenses where Raman spectroscopy on intact lenses is not applicable such determinations will be made on powder samples of insoluble protein which have been fractionated by PAGE-SDS electrophoresis. Fractions of both soluble and insoluble proteins will be subjected to longwave UV radiation and monitored for changes by absorption and Raman spectroscopy. The distribution of tryptophan in human lenses and cataracts will be determined to test the hypothesis that the linkage of protein molecules by activated tryptophan or its photoproducts is a significant cause of lens nuclear hyper-pigmentation and opacification.